Polyvinyl acetals are commercially valuable resins used as interlayers for safety glass, in adhesives, as epoxy resin plasticizers and as wash primers. They are derived from the reaction of poly(vinyl alcohol) with aldehydes, but can be prepared by a one-step process in which a poly(vinyl ester) such as poly(vinyl acetate), is simultaneously saponified and acetalized.
The properties of polyvinyl acetals depend upon the method of preparation and the proportion of residual unhydrolyzed ester groups, the number of alcohol groups and the percentage of acetal moieties contained in the polymer. For example, in the preparation of safety glass, a polyvinyl butyral is used having a small amount of vinyl acetate, about 9% of vinyl alcohol groups, and about 70-80% of vinyl butyral groups. Polyvinyl butyral L resins used in wash primers have about 2-3% of residual vinyl acetate in the polymer. Other applications, such as in specialty adhesives, textile coatings or strippable coatings require different polymer compositions.
One method of modifying the properties of polyvinyl acetals has been to change the functionality of monomers making up the polymer, such as employing a comonomer with the vinyl alcohol monomer, such as acrylonitr vinyl chloride, acrylate and the like. A discussion of polyvinylacetals and such modification using acetalized vinyl alcohol copolymers is given by Lindemann. Encyclopedia of Polymer Science and Technology. Volume 14pages 208-239 (1971). It is desirable however to improve on the forms and functionality of polyvinylacetals in order to increase their
Amine functional polymers are valuable as a cost effective way of incorporating cationic charge into polymers useful in cationic electrocoating, water treatment, and enhanced oil recovery (EOR). U.S. Pat. No. Lai et al. (1989) discloses the use of high molecular weight (&gt;1.times.10.sup.6) poly(vinylamines) in acidized fracturing fluids for EOR. Such poly(vinylamines) can be prepared by acid or base hydrolysis of poly(N-vinylformamide). Although the high molecular weight poly(vinylamines) can be used in EOR without crosslinking, the use of crosslinking agents, such as epichlorohydrin, hexamethylene diisocyanate and glyoxal, is disclosed as optional The use of a dialdehyde. such as glyoxal, to crosslink poly(vinylamine) is also disclosed in Japanese Patent Publication No. J61051006 (1986).